Harmony and Conflict in the Living World - Alexander F. Skutch [18]
The most probable explanation of senescence and death is that it is an evolved character, programmed by the genes. An animal is born with the seeds of its decay within it. Evolution depends upon the continuous replacement of individuals; only populations can evolve. The adaptability of individuals, limited by their heredity, may not be great enough to adjust them to changing environments. Perhaps, in the long history of the living world, species composed of potentially immortal individuals arose, only to become extinct because they lacked the flexibility that death and mutability give a species to adjust to changing conditions. Creatures die to give their species the adaptability to survive in a world of change, or to rise to higher levels of organization and mentality. After working hard to replenish its species, the individual, even in the absence of external causes, passes away, reducing by one the numerical strength of the species. Far from doing nothing for the good of its species, willingly or unwillingly the individual makes the supreme sacrifice for its species. It owes its life to the species; it relinquishes its life for the benefit of its species.
Contemporary biologists, who view all organisms as ceaselessly engaged in a relentless struggle to increase their individual fitness, as measured by the number of their progeny, use all their ingenuity to explain puzzling examples of animal behavior in ways that support their theories. They appear to delight in detecting trickery and deception in animal life. Thus, the much-discussed
Page 31
"beau geste" hypothesis holds that a bird sings a variety of songs in different parts of his territory to make it appear that several individuals are settled in it, thereby discouraging other males from trying to intrude. When a bird feeds nestlings or fledglings of a different species, this is a "mistake." In both of these situations, alternative explanations deserve consideration: the singer may repeat several songs because he enjoys hearing them, or because a varied repertoire, like bright plumage, makes him more attractive to females in search of a partner; the altruistic bird, well aware that the alien nestling is not its own, is moved by the youngster's pleas for food. Since we cannot read the mind of a bird, we cannot be sure which of the alternative explanations is correct; but consistently to choose the harsher interpretation makes life appear more sordid than it may actually be. Ought we not to welcome any indication among nonhuman creatures of the psychic or moral attributes that we admire in ourselves, and do our best to substantiate them? The more cooperation or kindness that we can detect in other branches of the animal kingdom, the more hopeful our own future becomes. Certainly the living world contains enough that is obviously repugnant or distressful to contemplate, without increasing its apparent amount by forced interpretations. Since, whether we like it or not, we belong to the living world, some of us wish to think well of it. Because genes impel animals to increase their own fitness, as measured by the number of their progeny, often regardless of consequences to other members of their species or to other species, they have been called "selfish.''
But, as we have seen, creatures so motivated squander their strength, expose themselves to perils, and often debilitate themselves to perpetuate their species. Finally, if no accident befall them, they grow senile and die to give their species the flexibility to confront changing